minor #30019 [Mime] improve some types in docblocks (xabbuh)

This PR was merged into the 4.3-dev branch.

Discussion
----------

[Mime] improve some types in docblocks

| Q             | A
| ------------- | ---
| Branch?       | master
| Bug fix?      | no
| New feature?  | no
| BC breaks?    | no
| Deprecations? | no
| Tests pass?   | yes
| Fixed tickets |
| License       | MIT
| Doc PR        |

Commits
-------

27463daced [Mime] improve some types in docblocks

src/Symfony/Component/Mime/MimeTypeGuesserInterface.php

@@ -28,7 +28,7 @@ interface MimeTypeGuesserInterface
      *
      * @param string $path The path to the file
      *
-     * @return string The MIME type or null, if none could be guessed
+     * @return string|null The MIME type or null, if none could be guessed
      *
      * @throws \LogicException           If the guesser is not supported
      * @throws \InvalidArgumentException If the file does not exist or is not readable

src/Symfony/Component/Mime/MimeTypes.php

@@ -35,6 +35,10 @@ namespace Symfony\Component\Mime;
 final class MimeTypes implements MimeTypesInterface
 {
     private $extensions = [];
+
+    /**
+     * @var MimeTypeGuesserInterface[]
+     */
     private $guessers = [];
     private static $default;
 

src/Symfony/Component/Mime/MimeTypesInterface.php

@@ -19,14 +19,14 @@ interface MimeTypesInterface extends MimeTypeGuesserInterface
     /**
      * Gets the extensions for the given MIME type.
      *
-     * @return array an array of extensions (first one is the preferred one)
+     * @return string[] an array of extensions (first one is the preferred one)
      */
     public function getExtensions(string $mimeType): array;
 
     /**
      * Gets the MIME types for the given extension.
      *
-     * @return array an array of MIME types (first one is the preferred one)
+     * @return string[] an array of MIME types (first one is the preferred one)
      */
     public function getMimeTypes(string $ext): array;
 }